Hollow drill rod for slurry application in a geothermal loop

ABSTRACT

A drill rod combination for creating a closed loop geothermal hole in the ground. A combination hollow drill rod and slurry dispenser is connected to a slurry pump and direct slurry through the rod and dispenser while within the geothermal hole. The slurry exits the dispenser surrounding a heat exchange tube removably mounted to the dispenser and left in the hole when the drill rod and dispenser are withdrawn.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the field of devices andmethods for installing geothermal closed loops in the ground.

2. Description of the Prior Art

Geothermal heating and cooling systems operate by exchanging heatbetween the constant temperature ground and a heat exchange mediumcirculated in a tube extending through the ground. In order to cool abuilding, heat within the building flows into the coolant medium withinthe tube extending from the building and through ground. The reverse istrue when heating a building wherein heat from the ground flows into theheat exchange medium which is then circulated via the tube in thebuilding with the heat flowing from the tube into the building.

The tube must be inserted into the hole drilled in the ground. In orderto minimize the time and expense in inserting the tube, there isdisclosed herein means for holding the tube to the drill rod as thedrill is used to bore the hole in the ground. Once the hole is formed,the drill is pulled out of the hole leaving the heat exchange tubewithin the hole. A bearing and bracket located on the drill allows thetube to remain in a non-rotating status even though the drill isrotating into the ground. In order to further minimize rotation of thetube that might be caused by rotation of the drill, a rudder is providedon the tube engaging the ground thereby limiting rotation of the tube.

In order to allow the rudder on the tube to stay in contact with thesurrounding dirt, it is necessary to control the diameter of the holebeing formed by the drill bit. The drill bit and associated drill rodcomponents, must be of a certain size to enable the heat exchange mediumholder along with its bearing and tube to extend freely into the boredhole while at the same time insuring that the rudder on the tube engagesthe side wall of the bored hole.

A sonde is located along the length of the drill and is operable toindicate the location of the drill bit within ground. For example, onesuch sonde housing is available from Vermeer Corporation of Pella,Iowa—Part No. 22686638001. Sonde housings are available in differentdiameters; however, in one geothermal application, it is desired to usethe above-identified sonde housing having a relatively small diameter.The distal end of the sonde housing forms a drill bit mounting surfaceoriented at an angle relative to the axis of rotation of the drillthereby mounting the flat planar drill bit also at the same anglerelative to the axis of rotation. The teeth at the distal end of thedrill bit therefore project radially outward of the circumference of thesonde housing providing a larger than desired bored hole diameter. Inorder to eliminate this disadvantage, we have disclosed herein anadaptor, located between the drill bit and the sonde housing, having abeveled proximal end forming a mounting surface arranged at the sameangle relative to the axis of rotation as the distal mounting surface ofthe sonde housing. The opposite proximal end of the adaptor is containedwithin a plane extending in the same direction as the axis of rotationthereby mounting the drill bit in the same plane ensuring that the drillbit does not extend further outward than the desired diameter of thehole. The bit includes a width which extends sufficiently outward tocreate a hole to accommodate the heat exchange tube and associated mountwhile enabling the tube rudder to engage the bored hole side wallslimiting rotation of the tube even though the drill rod is rotating.

Once the heat exchange tube is inserted into the blind hole, it isdesirable to hold or set the heat exchange tube within the hole. Aflowable substance such as slurry is forced into the hole surroundingthe heat exchange tube thereby securing the tube in place. A variety offlowable substances may be used. Typically, a thin mixture of insolublematerial, such as cement, clay, coal, etc. with a liquid as water oroil.

The invention disclosed herein includes forcing the slurry through ahollow drill rod having a heat exchange tube attached to the drill rod.The distal end portion of the drill rod includes a plurality of outletsin communication with the passage extending through the drill rodallowing the slurry to exit into the blind hole. A mount on the drillrod removably holds the heat exchange tube. As the drill rod iswithdrawn from the hole, the heat exchange tube disengages the drill rodremaining in the hole and is surrounded by the slurry thereby holdingthe tube in place.

SUMMARY OF THE INVENTION

One embodiment of the present invention is a method of installing aU-shaped heat exchange tube of a geothermal closed loop system in ablind hole in the ground using a boring machine with a rotatable drillrod having a drill rod end portion and a drill bit for drilling theblind hole in the ground comprising the steps of providing a boringmachine, a hollow drill rod with a hollow drill rod end portion withoutlets and a drill bit. Further, a connecting device is provided toremovably connect a U-shaped heat exchange tube to the hollow drill rodend portion. The steps of the method include attaching the drill rod tothe boring machine, rotating the drill rod having the drill bit attachedthereto with the boring machine, moving the drill rod with the drill bitin a first direction into the ground during the rotating step to createthe blind hole having an entrance in the ground and a blind end with theblind hole extending at an acute angle relative to horizontal. Aflowable substance is forced through the drill rod and the drill rod endportion exiting via the outlets of the drill rod end portion into theblind hole. The drill rod and the drill rod end portion are moved in adirection reverse to the first direction while un-attaching the drillrod from the U-shaped heat exchange tube while the drill rod is in theblind hole. The drill rod is withdrawn from the blind hole therebyallowing the U-shaped heat exchange tube to remain in the blind hole andwhile held therein by the flowable substance.

A further embodiment of the present invention is a device for creating ageothermal closed loop using a U-shaped tube positioned in a blind holein the ground with the tube having an inlet portion and an outletportion extending out of the blind hole comprising a rotational hollowdrill rod having a first interior passage and a hollow drill end portionhaving a second interior passage in fluid communication with the firstinterior passage. The drill end portion has an outlet allowing flowablematerial to move through said first passage and the second passage toflow outwardly through the outlet into the blind hole. A pump isconnected to the drill rod to force flowable material therethrough. Ablade is mounted to the drill rod being sized for creating the blindhole. A U-shaped tube has an inlet portion and outlet portion forcirculating a medium therein. A mount on the hollow drill end portionremovably holds the U-shaped tube as the drill end portion is positionedin the blind hole but releases the U-shaped tube as the drill rod anddrill end portion are pulled from the blind hole leaving the tube withinthe blind hole and held therein by the flowable material.

Yet a further object of the present invention is a combination dispenserof slurry and a heat exchange tube holder to attach to a drill rodhaving a drill bit for creating a blind hole in the ground and with aheat exchange tube to be positioned therein comprising a main body witha proximal end mountable to the drill rod and having a passage thereinand a plurality of outlet holes allowing slurry forced through saidpassage to exit via the outlets into the blind hole to surround and setthe heat exchange within a blind hole. A mount on the main body holds aheat exchange tube within the blind hole when the main body is insertedinto the blind hole but allows disengagement of the heat exchange tubefrom the mount as the main body is withdrawn from the blind hole.

It is an object of the present invention to provide a new and improvedmethod for installing a tube of a geothermal closed loop system into theground.

A further object of the present invention is to provide a device for usein installing a u-shaped tube in the ground for use with a geothermalsystem.

In another object of the present invention is to provide a device forminimizing rotation of the heat exchange tube with respect to theattached drill rod as the drill rod is rotated into the ground.

In addition, it is an object of the present invention to provide anadaptor to facilitate the mounting of the drill bit to a sonde housing.

Yet a further object of the present invention is to provide a method anddevice for inserting a flowable substance into the blind hole tosurround the heat exchange tube therein.

Related objects and advantages of the present invention will be apparentfrom the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of the geothermal system installed on a lot.

FIG. 2 is a side elevation view of geothermal line 26 located beneaththe ground level.

FIG. 3 is a fragmentary perspective view of a conventional drill used indrilling a geothermal hole for use in practicing an alternate embodimentof the present invention.

FIG. 4 is a fragmentary, perspective view with u-shaped heat exchangetube attached to the drill end portion used in practicing anotheralternate embodiment.

FIG. 5 is a fragmentary side view of the drill rod connected by abearing to the heat exchange tube and an evacuation tube used topractice the method disclosed herein all according a further alternateembodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view taken along the line 6-6 ofFIG. 5 and viewed in the direction of the arrows.

FIG. 7 is an enlarged end view of the boring head shown in FIG. 5.

FIG. 8 is a fragmentary and exploded perspective view of the drill bitmounted to the sonde housing, in turn, mounted to the drill rod showingthe drill bit mounting adapter, heat exchange tube mount, and rudderedtube return loop incorporating an alternate embodiment.

FIG. 9 is an enlarged perspective view of the tube mount.

FIG. 10 is an enlarged perspective view of the return loop mounted tothe inlet and outlet tubes.

FIG. 11 is a cross-sectional view illustrating the internal passage ofthe return loop.

FIG. 12 is a cross-sectional view taken along the line 12-12 of FIG. 10and viewed in the direction of the arrows.

FIG. 13 is a bottom view of the return loop of FIG. 12.

FIG. 14 is a perspective view of an alternate embodiment of the returnloop.

FIG. 15 is a perspective view of the bottom half of the loop of FIG. 14.

FIG. 16 is a top view of return loop of FIG. 14.

FIG. 17 is an end view of the return loop of FIG. 14.

FIG. 18 is an enlarged perspective view of the drill bit mountingadapter.

FIG. 19 is a side view of the adaptor of FIG. 18.

FIG. 20 is a fragmentary, perspective view of a hollow drill rod with afixed heat exchange mount for the preferred embodiment of the presentinvention.

FIG. 21 is a fragmentary side view of the drill rod connected by abearing to the heat exchange tube for the first alternate embodiment ofthe preferred embodiment of FIG. 20.

FIG. 22 is an enlarged cross-sectional view taken along the line 22-22of FIG. 21 and viewed in the direction of the arrows.

FIG. 23 is a fragmentary and exploded perspective view of the drill bitmounted to the sonde housing, in turn, mounted to the drill rod showingthe drill bit mounting adapter, heat exchange tube mount, and rudderedtube return loop incorporating the second alternate embodiment of FIG.20.

FIG. 24 is an enlarged perspective view of the tube mount also shown inFIG. 23.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated device, and such further applicationsof the principles of the invention as illustrated therein beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates.

Referring to FIG. 1, there is shown a schematic top diagram of ageothermal system connected to a building. The building or house 20 isconstructed on lot 21 having side boundaries on 22 and 23 along with endboundaries 24 and 25. A driveway extends from the building to the streetor road. Six separate geothermal lines 26-31 extend beneath ground leveland fan out from a pit 32. Each geothermal line 26-31 is formed bydigging a blind hole into the ground with a separate geothermal tubepositioned within each hole forming the geothermal lines 26-31. Thetubes within the holes are then connected together funneling into anoutlet tube 34 and an inlet tube 35 leading to a conventional heatexchanger 36 located within or adjacent building 20.

Pit 32 is formed by rolling back a 4×6 foot area of sod usingconventional tools, such as, a backfill blade on an excavator. Pit 32 isthen dug to a depth of five feet and provides a starting point for thesix holes leading to the six geothermal lines 26-31. As each hole isdug, pit 32 provides a storage area for the removed dirt and water in aconfined area and also allows material to drain back into each boredhole as needed to pack around u-shaped tubes inserted into the six boredholes.

While the drawings show a total of six geothermal lines, it is to beunderstood that the present invention includes less than or more thansix lines depending upon the amount of heat exchange required forbuilding 20. Typically, each line must be approximately 150 feet inlength to provide one ton of air conditioning. In order to minimize thehorizontal space occupied by the lines, the bored holes are drilleddownward at an angle relative to horizontal. For example, in FIG. 2,line 26 includes a bored hole 36 at an approximate angle 17 of 19degrees relative to a horizontal line 18. By extending the bored holesdown at an acute angle relative to the horizontal, the length of thehole may be optimized given the limitation of the horizontal distancebetween the boundary lines 24 and 25 of the lot upon which the facilityis located.

In many cases, rock formations are located beneath ground level 33. Forexample, in the event a rock formation or rock layer exists 100 feetbelow ground level, then if the bored holes are drilled only in avertical direction, difficulty is incurred for drilling of a 150 foothole as the drill bit drills through the rock. Thus, by orienting thebored hole at an acute angle relative to horizontal, difficulties may beavoided from a rock formation while also maximizing the length of thehole relative to the boundaries of the lot. In the event the bored holesextend beyond the lot boundary line, then covenants may limit the sizingof the length of the hole. The method of the present invention thereforeincludes the step of orienting the drill rod with attached drill bit atan acute angle relative to horizontal as the hole is drilled in theground. In order to determine angle 17, the desired length of the boredhole must first be selected with the acute angle then being calculatedgiven the desired length and either the horizontal distance, permissibleby the lot boundaries, of the desired bored hole or the verticaldistance, permissible by the depth of rock formations, beneath ground towhich the hole is to extend.

Since pit 32 is only four to six feet across and five feet deep, it isnecessary to start boring the hole at a distance from the pit in orderto orient the hole at a 19 degree angle relative to horizontal. Thus,the drill bit is rotated into the ground at location 86 (FIG. 2) apartfrom the hole creating a 19 degree hole 85 which enters the pit sidewall 87 at location 88. The drill bit continues to rotate and moves intothe pit engaging the bottom wall of the pit creating entrance 55 of hole36 also oriented at a 19 degree angle relative to the horizontal. It isdesirable that hole 55 be created in the bottom wall of the pit in orderto allow the material from the hole to exit the hole into the pit andeventually move back into the hole once the heat exchange tube islocated in the hole.

Referring to FIG. 3, drill rod 42 has one end 41 attached to aconventional hole boring machine 39 such as available from VermeerCorporation of Pella, Iowa. Machine 39 has a rotatable output releasablyconnected to end 41 of rod 42 with the opposite end 43 of the rodconnected to a conventional drill bit end portion 38. In the alternateembodiment shown in FIG. 3, rod 42 and drill bit end portion 38 arerotated by machine 39 through the bottom of pit 32 (FIG. 2) creating ahole approximately four inches in diameter at a 19 degree angledepending upon the conditions of the ground. Each line is sized forapproximately one ton of cooling/heating for the geothermal systeminstalled. The entrance 55 of the hole 36 associated with line 26 isprovided at the bottom of pit 32. Likewise, each hole created for lines27-31 has a separate entrance.

Once a hole is created, the drill rod 42 and drill bit 38 are removedfrom the hole. Drill bit 38 is then unthreaded from rod 42 and a drillend portion 37 having a cone shaped closed end 46 (FIG. 4) is mounted torod 42. Bit 38 and end portion 37 have an internally threaded socketinto which the external threaded male end of rod 42 extends.

A hooked shaped arm 56 has a proximal end 53 mounted to end portion 37and forms an open end 52 facing away from rod 42. Arm 56 is used to pullthe u-shaped tube 45 (FIG. 4) into the hole once the hole has been boredand the drill rod 42 with end portion 37 is inserted into the hole.After end 46 reaches the blind end of the hole, the rod 42 with endportion 37 is pulled outward leaving the u-shaped tube 45 within thehole.

The u-shaped coolant tube 45 is mounted to the arm 56 by any number offastening means. For example, a cable 47 is extended through the spacebetween tube portion 48 and tube portion 49 of tube 45. The cable isextended around arm 56 between the space existing between arm 56 and themain body of end portion 37. A conventional cable clamp 50 then joinsthe opposite ends of cable 47 securing the u-shaped tube 45 to rod 42 byhooking the tube 45 to arm 56. So long as rod 42 and end 46 movedownward into the bored hole, the arm 56 is operable to pull tube 45into the hole. Once the drill rod 42 is moved in a direction opposite toarrow 51, cable 47 moves through open end 52 of arm 56 therebydisengaging cable 47 and tube 45 from the arm leaving in place, withinthe hole, tube 45 while the drill rod and drill end portion arecompletely removed from the bored hole. Excellent results have beenobtained by using a 3/16 inch braided cable for cable 47. The width ofthe cone shaped end 46 must be smaller than the diameter of drill bitend portion 38 so that the bored hole is sufficiently large relative tocone shaped end 46 to prevent interference of end 46 with tube 45 as end46 is pulled outward from the hole.

The opposite end portions 48 and 49 (FIG. 2) of tube 45 extend outwardthrough the entrance 55 of the bored hole and are connected to lines 34and 35, in turn, connected to heat exchanger 36 (FIG. 1). The oppositeend portions 45 and 49 are connected together by joint coupler 54. Thus,the heat exchange medium is circulated through outlet tube 34 in thedirection of arrow 51, through the tube portion 49 and then back throughcoupler 54 through tube portion 48 in the direction opposite of arrow 51to tube 35, in turn, connected to the heat exchanger.

In a similar fashion, a hole is bored for line 27 and then line 28 etc.until all of the bored holes are completed as just described with thedrill rod and drill bit then being withdrawn sequentially from eachbored hole with a separate u-shaped tube connected to arm 56 andinserted into each bored hole thereby forming geothermal lines 26-31. Aseach u-shaped tube is inserted in the particular bored hole, the waterand dirt within the pit is allowed to flow back into the bored hole.Once the inlet tube portion and outlet tube portion of each of the sixu-shaped tubes 45 are connected respectively to tubes 34 and 35, pit 32may be filled with the sod being replaced. Each of the bored holesforming lines 26-31 has a bottom blind end against which each coupler 54may rest. A universal coupler is used to join the end portions 49 toline 34 and end portions 48 to line 35.

An alternate embodiment for installing a geothermal closed loop employsthe tool shown in FIGS. 5 and 6. The tool allows for the u-shaped tubeto be installed into the bored hole at the same time the hole is beingcreated thereby eliminating one of the steps of the previously describedmethod. Further, the drill bit is not removed from the drill rod. Thus,drill rod 42 (FIG. 5) has one end 43 connected to drill end main body 95whereas the opposite end 41 is connected to boring machine 39. A bearing70 has an inner race 71 (FIG. 6) fixedly secured to the drill end mainbody 95 to prevent relative motion between race 71 and the drill rod anddrill end main body. The bearing includes an outer race 72 which freelyrotates on race 71. Bearing 70 employs conventional bearing constructiontechniques and is commercially available. Fixedly mounted to the outerrace 72 of bearing 70 is arm 56 having its proximal end 53 fixedlysecured to race 72. Cable 47 mounts the u-shaped tube 45 to arm 56 in anidentical manner as previously described. Thus, with rod 42 and drillend main body 95 rotating, outer race 72 will remain stationary therebyallowing tube 45 to be in a non-rotating condition.

A ¾ inch hose 76 has a proximal end 77 mounted by a conventional clamp78 to the outer race 72. The opposite end 79 of hose 77 extends outwardfrom the entrance 55 of the hole and it is connected to a conventionalpump to facilitate extraction of water and dirt from the hole as thehole is being bored and to also allow the pump to force the water anddirt back into the bored hole as the drill rod and drill bit areremoved. Each hole is drilled by rotating rod 42 and drill bit main body95 while at the same time carrying the u-shaped tube 45 into the boredhole being created. End 98 of drill bit main body 95 is fixedly attachedto a conventional flat drill bit 94 to rotate therewith.

The blind holes are formed in a manner identical as previouslydescribed. For example, bored hole 36 has an entrance 55 located at thebottom of pit 32 and is angularly positioned relative to the horizontalat angle 17. The length of the bored hole and the acute angle 17 arecalculated as previously described. Drill bit 94 advances into theground creating the bored hole with the u-shaped tube 45 pulled into thehole behind the drill bit at the same time that the hole is being bored.Once drill bit 94 reaches the desired length of the bored hole creatinga blind hole end, the drill bit and drill rod are pulled in a directionopposite of arrow 51 thereby allowing the u-shaped tube to remain in thebored hole since cable 47 disengages arm 56.

Drill bit 94 (FIG. 7) has a flat blade boring head operable to bore ahole having a diameter equal to the length 95 of the blade. Thus, thehole is sized to allow for movement of tubes 45 and 76 into the hole asit is bored. When withdrawing the blade from the hole it may benecessary to rotate the blade until the blade is past the tube 45 whichremains in the hole. Since hose 76 is fixedly fastened to the outerbearing race 72, the hose is withdrawn from the bored hole along withthe drill rod and drill bit.

Commercially available monitors are available for locating and fordetermining the depth and horizontal distance the drill bit extends.Likewise, the angular position of the drill bit about its longitudinalaxis may also be determined by such monitors. For example, DigitalControls, Inc., Kent, Wash. distributes a directional drill locatingsystem under the model, name and number Digitrack F2. The Digitrack F2directional drill locating systems includes a sensor mountable withinthe drill rod that is operable to transfer back to a remote monitor theroll, pitch, signal strength, temperature and real time as well asindicate the horizontal distance of the drill bit from the monitor andthe depth beneath the ground. The drill rod, drill bit and hose areextracted from the bored hole while the slurry water mixture is pumpedback into the bored hole ensuring the void in the soil is completelyfilled.

FIG. 8 shows a fragmentary perspective view of an alternate embodimentof the present invention including the adaptor for mounting the drillbit to the sonde housing and the drill rod bearing mount to removablyhold the return loop having the inlet and outlet heat exchange tubesextending therein with the loop having an outwardly extending rudder toengage the side wall of the hole. Drill rod 100 has its proximal enddrivingly connected to boring machine 39 as previously explained fordrill rod 42. Instead of the distal end 101 being attached directly tothe drill bit as illustrated for the distal end 38 (FIG. 3), the distaldrill end 101 is connected to a commercially available sonde housing102, in turn, connected to a drill bit adaptor 103, in turn, connectedto drill bit 104. A bearing 105 is rotatably mounted to drill rod 100and includes a sleeve or collar 106 having an inside diameter largerthan the outside diameter of drill rod 100 to enable collar 106 toremain in a non-rotating condition even though drill rod 100 rotates. Aplurality of headed fasteners 107 are mounted to either side of collar106 to prevent the collar from cocking. The heads of fasteners 107contact the side surfaces 108 (FIG. 9) of the collar limiting movementof the collar in a longitudinal direction along the axis of rotation 109of the drill rod. Collar 106 provides a mount for removably holding theheat exchange tube as the drill rod is advanced into the ground.

Collar 106 includes an arm 110 that extends radially outward from rod100 and then forwardly towards the drill bit 104 forming a finger 111which is removably extendable into the return loop of the heat exchangetube. The return loop includes at least two different forms. In thefirst form, return loop 112 (FIG. 10) has a generally v-shapedconfiguration and is designed to be joined by fusing or other means tothe heat exchange inlet tube 114 and the heat exchange outlet tube 115.In the second form, the return loop 113 (FIGS. 14 and 16) has a clamshaped configuration and is designed to receive the heat exchange tubewhen the tube consists of a single u-shaped tube that is distinguishedfrom the two separate tubes 114 and 115 depicted in FIG. 10. In otherwords, in the event inlet tube 114 and outlet tube 115 are joinedtogether in a u-shaped configuration, then the u-shaped configurationmay be inserted into the return loop 113.

Both return loops 112 and 113 have a slot 118 for receiving theforwardly extending finger 111 (FIG. 9) and also include a rudder 120extending outwardly therefrom to engage the side walls of the boredhole. Return loop 112 includes an inlet 116 and an outlet 117 with apassage 119 formed therein. Inlet tube 114 extends into inlet 116 and isjoined to the main body of the return loop 112 by fusing or othersuitable means allowing the heat exchange medium to flow from tube 114and into passage 118 and then backward to the outlet 117 to outlet tube115. Similarly, outlet tube 115 is joined to the main body of the returnloop and extends into opening 117 being joined thereto by fusing orother suitable means. The rectangular slot 118 opens rearwardly at thesame end as the location of inlet 116 and outlet 117 and is positionedtherebetween. Slot 118 is sized to slidably and removably receive finger111 of the downwardly extending mount arm 110. Thus, as the drill rodwith the bit is advanced rotatingly into the ground forming the hole,tubes 114 and 115 are carried by finger 111 until the drill rod ispulled outwardly from the hole thereby enabling finger 111 to slide outof slot 118 disengaging return loop 112 leaving the return loop alongwith tubes 114 and 115 within the hole.

A rudder 120 is integrally joined to the main body of return loop 111and extends outwardly therefrom with the outer edge 121 of the rudderfrictionally engaging the side walls of the hole limiting or preventingrotational movement of return loop 112 and tubes 114 and 115 even thoughthe drill rod is being rotated. The leading edge 122 of rudder 120 isreduced and sized or may be pointed to allow the rudder to extend intothe dirt as the drill rod is rotated into the ground.

The second form of the return loop is depicted in FIG. 14. Return loop113 has a construction forming two main body portions 130 and 131cooperatively forming an inlet 132 and an outlet 133 and an internalcavity extending therebetween. Portions 130 and 131 are secured togetherby conventional fastening devices 134 (FIG. 16) once the heat exchangetube is positioned within and between portions 130 and 131. Return loop113 is particularly useful when inlet tube portion 114 and outlet tubeportion 115 are a single tube having a u-shaped configuration with theu-shaped configuration being positionable within the internal cavity 136(FIG. 16) extending between the inlet 132 and outlet 133. A portion ofthe interior side wall 135 forming cavity 136 is curved to facilitatethe u-shaped configuration of inlet portion 114 and outlet portion 115.Thus, a single tube may be bent to form a u-shaped configuration withthe u-shaped configuration then positioned in cavity 136.

Slot 118 previously described for return loop 112 is also provided onreturn loop 113 to allow the return loop to slidingly engage the finger111 (FIG. 9) as the mount with drill rod are inserted into the ground.Removal of the drill rod out of the bored hole allows the finger 111 todisengage slot 118 as previously described allowing return loop 113 andthe heat exchange tube formed by tube portions 114 and 115 to remain inthe hole. Similarly, a rudder 120 is cantileverly mounted to portion 131and extends outwardly therefrom to engage the side wall of hole. Aspreviously detailed, the forward or leading end 122 of rudder 120 may betapered to facilitate insertion of return loop 113 into the ground asthe hole is being formed by the rotating drill rod and drill bit.Likewise, rudder 120 is positioned between inlet 132 and 133 andtherefore positioned between the single tube formed by inlet tubeportion 114 and outlet tube portion 115.

The return loops 112 and 113 when used in combination with the mount 105and drill rod are particularly useful during the creation of ageothermal ground hole with the heat exchange inlet tube portion andoutlet tube portion positioned and extending out of the hole. The drillrod and bit as they are advanced into the ground boring the hole carrythe return loop and heat exchange tube into the hole with the drill bitand drill rod then being removed from the hole leaving the heat exchangetube therein. When combined with the adaptor 103 (FIG. 8) the resultantcombination allows for optimum boring of the geothermal hole andplacement of the heat exchange tube in a one step operation.

The commercially available sonde housing 102 (FIG. 8) includes aproximal end 160 having a male threaded end portion that extendsmeshingly into an internally threaded socket in the distal end 101 ofdrill rod 100. The main body of sonde 102 is cylindrical and has an axisof rotation the same as axis 109 for drill rod 100. Such a sonde isavailable from Vermeer Corporation of Pella, Iowa under Part No.22686638001. The distal end 161 of the sonde main body has a beveledmounting surface 162 arranged at an acute angle 163 relative to axis ofrotation 109. The adaptor 103 (FIG. 8) has a cylindrical main body andhas the same axis of rotation as axis 109. Adaptor 103 (FIG. 19) has abeveled mounting surface 164 arranged at the same angle 163 relative toaxis of rotation 109. Adaptor 103 is flat at its distal end 166 having adrill bit mounting surface 167 that is located in a plane extending inthe same direction and containing the axis of rotation 109 of theadaptor which is the same as axis 109 of drill rod 100.

Drill bit 104 (FIG. 8) is commercially available and is flat extendingin a plane from the bit proximal end 168 to the bit distal end 169. Aplurality of cutting teeth are located on end 169. The drill bitproximal end 168 has a mounting surface 170 that is flat and restsagainst adaptor surface 167 being secured thereto by a plurality ofconventional fasteners 171 that extend from drill bit proximal end 168through surfaces 170 and 167 into the distal end 166 of the adaptorthereby securing the drill bit to the adaptor. Likewise, a plurality ofconventional fasteners 172 extend from the proximal end 165 of adaptor103 through surfaces 162 and 164 and into the distal end 161 of sondehousing 102 thereby securing the adaptor to the sonde housing. Sincesurfaces 162 and 164 are in the same plane and arranged at the sameacute angle relative to axis 109 and since surfaces 167 and 170 are inthe same plane extending in the same direction as axis 109, the adaptorpositions the flat drill bit to extend in the same direction as the axisof rotation even though the sonde distal end has a beveled mountingsurface. Thus, the drill bit does not enlarge the diameter of the holewith the exception that the width of the drill bit causes the teeth tobe located outwardly of the cylindrical sonde body. The diameter of thehole can therefore be selected depending upon the width of the drill bitin order to ensure that the rudder engages the side of the hole limitingrotation and twisting of the heat exchange tubes even though the drillrod is rotating.

The preferred embodiment of the present invention is shown in FIG. 20.The embodiment of FIG. 20 has the hooked-shape arm fixedly attached tothe drill rod such as described for the embodiment of FIG. 4. In theFIG. 20 embodiment, the drill rod and drill rod end portion are hollowto allow slurry or other flowable substance to be forced to the drillrod exiting the drill rod end portion through outlets therebysurrounding the heat exchange tube located within the blind hole. Thewater and evacuation hose 76 described in the embodiment in FIG. 5 isnot used with the hollow drill rod and drill rod end portion shown inFIG. 20.

Device 200 includes a rotational hollow drill rod 201 having an interiorpassage 202 that extends from the proximal end 203 of the drill rod tothe drill rod distal end 204. Drill rod 201 is shown in fragment toillustrate the interior passage as is dispenser 209.

The proximal end 203 is attached to a conventional hole boring machine206, such as available from Vermeer Corporation of Pella, Iowa. Machine206 has a rotatable output releasably connected to proximal end 203 ofdrill rod 201. Further, a high pressure pump 207 is connected toproximal end 203 of the drill and is operable to force a flowablesubstance, such as slurry, downwardly through the interior passage 202and then through a second interior passage 208 of a combinationdispenser of slurry and heat exchange tube holder 209. Dispenser 209 hasa proximal end 205 sealingly connected to the distal end 204 of drillrod 201. Passages 202 and 208 are in fluid communication with eachother. A flowable substance is forced through the passages 202 and 208by pump 207 then exiting a plurality of outlets 210 allowing theflowable substance within passage 208 to flow outwardly of the dispenserand surround the heat exchange tube positioned within the blind hole.

High pressure pumps 207 are commercially available from the same VermeerCorporation that produces the conventional hole boring machine 206.

The distal end of dispenser 209 is connected to a cone shaped closed end212. A hook-shaped arm 213 has its proximal end 214 fixedly attached todispenser 209 with the distal end 215 of the hooked shaped arm pointingtowards cone shaped closed end 212 forming a gap 216. The U-shaped heatexchange tube 217 includes a pair of parallel tubes 218 and 219 joinedtogether by a hollow elbow tube 220 with the opposite ends of heatexchange tubes 218 and 219 extending out of the blind hole and connectedto the source 207 of heat exchange fluid. As previously described forthe embodiment of FIG. 4, a cable connects the heat exchange tube to thehook-shaped arm. Thus, cable 221 extends around elbow tube 220 and arm213 and is used to pull the U-shaped tube 217 into the hole once thehole has been bored in the drill rod. The drill rod, dispenser 209, anddrill bit is withdrawn from the hole with the drill bit being removedand the cone shaped end 212 then mounted to the end of dispenser 209.The U-shaped tube is then attached to the hook-shaped arm 217 aspreviously described with the combination then inserted back into theblind hole. After the cone shaped end 212 reaches the blind end of thehole, the slurry is pumped through the hollow drill rod and dispenser209 exiting via holes 210 surrounding the U-shaped tube 217. The drillrod is then pulled outwardly leaving the U-shaped tube 217 within thehole since cable 221 moves through the gap 216 in the direction of arrow225 as the drill rod is pulled outwardly in a direction opposite ofarrow 225.

Device 200 is used in the two step process with the first step having adrill bit attached to the distal end of dispenser 209 with the drill rodthen being rotated to create the blind hole in the ground for thesubsequent insertion of the heat exchange tube 217. The second step iswithdrawing the drill rod, replacing the drill bit with the cone shapedend 212 and attaching the heat exchange tube 217 to arm 213. Theresultant combination is then reinserted into the hole thereby carryingthe heat exchange tube to the blind end of the hole with the drill rodthen being withdrawn leaving the heat exchange tube within the hole.

The first alternate embodiment of the preferred embodiment shown in FIG.20 is depicted in FIG. 21. Device 230 (FIG. 21) is identical to device200 with the exception that device 230 is used as a one step process inthat the drill is used to form the hole at the same time the heatexchange tube is inserted into the hole. Thus, the drill bit 231 isattached to the distal end of dispenser 209, in turn, having itsproximal end attached to drill rod 201, in turn, driven by machine 206with the substance, such as slurry, being forced by pump 207 throughdrill rod 201 and dispenser 209 as described for the embodiment of FIG.20.

In order to prevent the heat exchange tube from rotating with the drillrod as the drill bit is rotated creating the blind hole, the heatexchange tube is mounted to a rotary mount 232.

Mount 232 has an inner race 233 fixedly mounted to dispenser 209 toprevent relative motion between race 233 (FIG. 22) and the dispensermain body whereas the outer race 234 freely rotates on the inner race233. Mount 232 employs conventional bearing construction techniques andis commercially available. Fixedly mounted to the outer race 234 is arm213 as previously described. A strap or cable 221 then extends throughthe gap 216 and onto arm 213 and also around elbow connector 220 of heatexchange tube 217. Drill rod 201 and dispenser 209 include the hollowpassages 202 and 208 previously described for the embodiment of FIG. 20.Likewise, a plurality of outlets 210 are provided on the dispenser toallow the slurry or other flowable substance to flow outwardly from thedispenser into the blind hole thereby surrounding the heat exchangetube. Once the drill bit 231 has reached the blind end of the hole beingcreated, the slurry is forced downwardly through the drill rod anddispenser exiting the dispenser and surrounding the heat exchange tubewith the drill rod, dispenser, and the drill bit then being withdrawnfrom the blind hole leaving in place the heat exchange tube.

A second alternate embodiment of the preferred embodiment of FIG. 20 isshown in FIGS. 23 and 24. In lieu of utilizing the rod shaped arm 213(FIG. 20), a plate shaped arm projects rearwardly from a ring bearing301 rotatably mounted to hollow tube 302. The proximal end 303 of hollowtube 302 is secured to the hollow drill rod 305 whereas the oppositedistal end 304 of tube 302 is secured to either the drill bit 104 or asonde tube 102 which may be positioned between tube 302 and drill bit231 and connected thereto by the adaptor previously explained for theembodiment of FIG. 8. Tube 302 has a plurality of apertures 315 allowingthe slurry forced through the hollow drill tube and into the hollowpassage of tube 302 in a manner identical to that described for theembodiment of FIG. 20. A plurality of projections 107 are mounted totube 302 and limit movement of ring bearing 301 along the longitudinalaxis of tube 302 in a manner identical to that described for theembodiment of FIG. 8. Ring bearing 301 has an inner race fixedly mountedto tube 302 preventing relative motion between the inner race and tube302 with the outer race rotatably mounted by bearings to the inner raceallowing the outer race and plate shape member 300 to remain stationarywhile the tube 302 rotates. Plate shape member 300 projects outwardlyfrom ring bearing 301 and toward the distal end 304 of tube 302 forminga gap 310 to receive either the elbow tube 220 (FIG. 21), or the returnloops 112-116 (FIGS. 10-17).

The blind hole formed by the embodiment shown in FIGS. 20-24 has anentrance at the bottom of a pit with the hole extending downwardly therefrom at an acute angle relative to ground level. As the drill rod isremoved from the hole, the drill rod, and drill bit are rotated therebyallowing the slurry being forced through the drill rod to be dispensedvia outlets 210 and distributed around the U-shaped tube which isstationary and left in the hole. The dispenser of the slurry may be thecombination slurry dispenser and heat exchange holder 209 (FIG. 20) orthe combined tube 302 with exits 315 and ring bearing 301 (FIG. 24).

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred and alternate embodiments have been shown anddescribed and that all changes and modifications that come within thespirit of the invention are desired to be protected.

What is claimed is:
 1. A method of installing a U-shaped heat exchangetube of a geothermal closed loop system in a blind hole in the groundusing a boring machine with a rotatable drill rod having a drill rod endportion and a drill bit for drilling the blind hole in the groundcomprising the steps of: providing a boring machine, a hollow drill rodwith a hollow drill rod end portion with outlets and a drill bit, andfurther providing a connecting device to removably connect a U-shapedheat exchange tube to said hollow drill rod end portion; attaching saiddrill rod to said boring machine; rotating said drill rod having saiddrill bit attached thereto with said boring machine; moving the drillrod with drill bit in a first direction into the ground during therotating step creating the blind hole having an entrance in the groundand a blind end with the blind hole extending at an acute angle relativeto horizontal; forcing a flowable substance through said drill rod andsaid drill rod end portion exiting via the outlets of said drill rod endportion into said blind hole; moving the drill rod and the drill rod endportion in a direction reverse to said first direction whileun-attaching the drill rod from said U-shaped heat exchange tube whilesaid drill rod is in the blind hole; and, withdrawing the drill rod fromthe blind hole while allowing said U-shaped heat exchange tube to remainin the blind hole being held therein by said flowable substance.
 2. Themethod of claim 1 and further comprising the step of: rotating saiddrill rod during said forcing step to distribute said substance aroundsaid U-shaped heat exchange tube.
 3. The method of claim 1 and furthercomprising the steps of: providing a hooked shaped arm forming saidconnecting device, said arm having a proximal end mounted to the drillrod end portion and a distal end forming a gap between the drill rod endportion and the distal end opening in a first direction toward the drillbit, and wherein said U-shaped heat exchange tube having an incomingtube portion and a return tube portion; removing the drill rod withdrill bit from the blind hole; removably connecting the U-shaped tube tothe hooked shaped arm; and, re-inserting the drill rod with the U-shapedtube attached to the drill rod end portion into the blind hole.
 4. Themethod of claim 1 and further comprising the steps of: attaching theU-shaped heat exchange tube to the drill rod end portion prior to saidmoving step so that the drill rod, drill bit and tube are moved into theground together while the blind hole is being created; restraining thetube from rotating as the drill rod and drill bit are rotated in theblind hole; providing means on the drill rod to removably hold the tubein a non-rotating condition as the drill rod rotates; removably mountingthe tube to the means prior to said moving step so that the drill rod,drill bit, means and tube are moved into the ground together while theblind hole is being created with the tube located on the means to fitwithin the hole being created by the drill bit.
 5. A device for creatinga geothermal closed loop using a U-shaped tube positioned in a blindhole in the ground with the tube having an inlet tubular portion and anoutlet portion extending out of the blind hole comprising: a rotationalhollow drill rod having a first interior passage and a hollow drill endportion having a second interior passage in fluid communication withsaid first interior passage, said drill end portion having an outletallowing flowable material moving through said first passage and saidsecond passage to flow outwardly through said outlet into said blindhole; a pump connected to said drill rod to force flowable materialtherethrough; a blade mounted to said drill rod being sized for creatingthe blind hole; a U-shaped tube having an inlet tubular portion andoutlet tubular portion for circulating a medium therein; a mount on saidhollow drill end portion removably holding the U-shaped tube as thedrill end portion is positioned in said blind hole but releasing theU-shaped tube as the drill rod and drill end portion are pulled from theblind hole leaving the tube within the blind hole and held therein bysaid flowable material; and, a bearing on said drill rod end portionhaving said mount removably holding the U-shaped tube in a non-rotatingposition as said drill rod rotates as the blind hole is being created byrotating the drill rod and drill end portion but releasing the U-shapedtube as the drill rod and drill end portion are pulled from the blindhole leaving the tube within the ground.
 6. A combination dispenser ofslurry and a heat exchange tube holder to attach to a drill rod having adrill bit for creating a blind hole in the ground and with a heatexchange tube to be positioned therein comprising: a main body with aproximal end mountable to said drill rod and having a passage thereinand a plurality of outlet holes allowing slurry forced through saidpassage to exit via said outlets into said blind hole to surround andset said heat exchange within a blind hole; and a mount on said mainbody to hold a heat exchange tube within the blind hole when said mainbody is inserted into said blind hole but to allow disengagement of saidheat exchange tube from said mount as said main body is withdrawn fromthe blind hole; and said mount includes a bearing rotatably mountingsaid mount to said main body allowing said heat exchange tube on saidmount to remain stationary as said main body rotates with said drillrod.
 7. The combination dispenser of slurry and a heat exchange tubeholder of claim 6 wherein: said mount includes a hook shaped arm with aproximal end mounted to said drill rod and a distal end forming a gapbetween said distal end and said drill rod with said gap opening towardsaid drill bit.
 8. The combination dispenser of slurry and a heatexchange tube holder of claim 7 wherein: said mount includes a connectorextending through said gap and onto said heat exchange tube removablyholding said heat exchange tube to said mount.
 9. A combinationdispenser of slurry and a heat exchange tube holder to attach to a drillrod having a drill bit for creating a blind hole in the ground and witha heat exchange tube to be positioned therein comprising: a main bodywith a proximal end mountable to said drill rod and having a passagetherein and a plurality of outlet holes allowing slurry forced throughsaid passage to exit via said outlets into said blind hole to surroundand set said heat exchange within a blind hole; and a mount on said mainbody to hold a heat exchange tube within the blind hole when said mainbody is inserted into said blind hole but to allow disengagement of saidheat exchange tube from said mount as said main body is withdrawn fromthe blind hole and, wherein: said main body and mount are fixedlysecured together limiting relative motion therebetween, said mountincludes a hook shaped arm with a proximal end mounted to said drill rodand a distal end forming a gap between said distal end and said drillrod with said gap opening toward said drill bit.